Retro-bolting is a term used within the rock climbing community to refer to the addition of new bolts to an existing climb. Retro-bolting can be contrasted with re-bolting, which is the replacement of existing bolts on a climb with new bolts.
There are many ethical issues relating to retro-bolting which can divide climbers into two camps, those for and those against.
Read more about Retro-bolting: Background, Outcomes